In the field of munitions it is often necessary to attack targets which are armored so that simple explosion of a munition against the armor is not sufficient to disable the target. For such use there have been developed projectiles known as "penetrators" which are not necessarily explosive on impact, but are of density, configuration, and propulsive force sufficient for maximum penetrating effects. One such device is known as a "long rod" penetrator: it is of dense metal such as a tungsten alloy, and is of relatively small diameter compared to the bore of the cannon generally available. It extends along a longitudinal axis from a forward, aerodynamic point to a rearward stabilizing fin structure. To obtain sufficient propulsion force, it is necessary to make these projectiles parts of munitions having cartridge cases several times the diameter of the body of the projectile, although of course the mouth of the cartridge case must be large enough to pass the rearward fin structure of the projectile. Means must also be provided for guiding the relatively small penetrator down the larger barrel of the firing piece and preventing the escape of propulsive gases down the barrel past the projectile.
These functions have been accomplished in the past by providing the penetrator with circumferential external buttress grooves along its midportion and engaging similar internal grooves in a bi-partite "sabot" secured in place by a loosely fitting "obturator ring" of nylon which rides in the rifling of the discharging barrel, thus preventing escape of propulsion gases. Rearwardly the sabot is grooved for crimped connection with the mouth of the cartridge case, within which the fin structure of the penetrator is received. Forwardly the sabot is configured to cooperate with a protective cap during travel through the barrel: cap, ring, and sabot separate from the penetrator upon leaving the barrel, to avoid increasing the drag of the penetrator during flight.